The invention relates to a winding unit with a wire magazine for use in a winding machine, particularly for the winding of wire on elongate particularly closed core members, such as toroidal cores.
In existing machines for the winding of toroidal cores, primarily with wire-shaped material, winding units with magazines are used which are mainly of the following kinds:
(1) The coil magazine type,
(2) The tubular magazine type,
(3) The double ring type,
(4) The single ring type,
(5) The bandaging type.
In winding units of the coil magazine type such as known, e.g. from German published specification DE-AS No. 1 228 719, the coil magazine moves in a circular path around the member to be wound ahd rotates simultaneously around its own axis. The disadvantages of this construction are that the winding material must be coiled into the coil magazine in a preceding operation, and that the supply capacity is limited relative to the dimensions of the circular path on one hand, and of the member to be wound on the other hand. In the winding of toroidal cores, whether they are open or endless, the coil magazine and thereby the supply capacity will be limited by the hole of toroidal core which is also a disadvantage.
In the tubular magazine type such as known e.g. from U.S. Pat. No. Re. 17,559, a tube is used which is bent into a circular ring in which the winding material is forming a spiral. During the winding operation the ring is rotating in its own plane around its own centre and around the member to be wound. The disadvantage of this construction is that the winding material must be twisted and pushed into the tube by means of special apparatus in a preceding operation.
A winding unit of the double ring type such as known from British Patent Specification No. 660 218, consists of an advancing ring and a magazine ring. The two rings have nearly the same diameter and a common axis of revolution. The disadvantage of this construction is that the two rings must first perform an interlocked rotary movement when positioning the winding material on the magazine ring whereafter the interlocking engagement is interrupted, the direction of rotation is reversed, and the winding may take place in a manner analogous to the two above mentioned methods. The fact, that in the double ring type the cross-sectional area is increased relative to that of the tubular magazine type due to the advancing ring, implies that the minimum value of the hole in toroidal cores, whether they are open or endless, will be increased.
In the single ring type such as known e.g. from U.S. Pat. No. 3,662,965 an endless ring is used having a U-shaped cross-section, said ring being provided with a lateral slide.
The disadvantage of this type is that the ring must first rotate a number of revolutions for positioning the winding material on the magazine whereafter the direction of rotation is reversed, and the winding may take place via the lateral slide in a manner analogous to the double ring type. In toroidal cores, whether they are open or endless, the winding plane will be displaced from the centre of the hole, whereby the wire consumption will increase. Furthermore, the minimum value of the hole of the toroidal core will be increased with the thickness of the lateral slide.
The bandaging machine is used to cover a finished winding with a strip-shaped insulating foil. Such a machine may have a magazine comprising two identical rings between which cylindrical rollers are closely arranged. In a machine disclosed in German published specification DE-OS No. 2 427 588 it has been attempted to use this principle for wire winding. When applied for wire winding the principle has two essential disadvantages. On one hand, the residual hole in the toroidal core will be great, since the wire supply is carried by the extreme part of the rollers having a flange only. On the other hand, due to the fact that the individual cylinders with flanges are rolling during the winding operation, a great friction will arise between the wire supply and the flange, and the wire will break if more than one wire layer is filled into the magazine.
Moreover, it is common to the magazine types described that the wire tension during the winding operation is provided by means of a friction brake. This type of brake can only act to increase the nominal level of wire tension without changing the variation range of the wire tension.
Some of the above-mentioned disadvantages are avoided in a winding machine of the single ring type disclosed in U.S. Patent Specificaion No. 2,974,890 in which the wire magazine is filled with winding wire in the same operation as the winding of a core by taking out the winding wire through a slit in the bottom of the wire magazine, i.e. the side facing the axis of revolution. However, in this prior art construction the need of accessability of the magazine from the external side results in a relatively open magazine in which no precautions have been taken for controlling the wire supply remaining in the magazine after cutting of the wire. Therefore, it will be necessary to fill wire into the magazine continouously to the end of the winding operation and, if the magazine should have a reasonable wire collecting capacity a considerable surplus of wire will be left in the magazine after completion of the winding operation and will get lost unless it is rewound from the magazine.
In another prior art winding machine disclosed in German Patent Specification No. 409,352 in which an open wire magazine is used having a very limited filling capacity the latter drawback is eliminated by fixing the free end of the wire relative to the magazine after cutting which requires, however, that rotation of the magazine is stopped momentarily.